The present invention relates to a method and a device for determining a prediction quality for a predicted energy consumption of a motor vehicle.
Current sensor data are currently predominantly used for controlling the drive train during engine control or in the operating strategy of motor vehicles, especially of electrified vehicles or hybrid vehicles, but the entire planned travel route is not taken into account. This is a disadvantage insofar as no optimal adaptation of the engine control or operating strategy to the planned route can be carried out.
Various methods have been developed in order to overcome said disadvantage. Thus e.g. a method for optimizing the driving mode of a motor vehicle based on a plurality of parameters is known from DE 10 2008 035 944 A1, wherein a travel route of the vehicle is determined by specifying a destination, a plurality of different route parameters that are characteristic of a profile of the determined travel route of the vehicle between the geometric location or a starting point of the vehicle journey and the destination, are determined, and at least one travel condition is determined that is characteristic of the determined travel route of the vehicle between the geometric location of the vehicle or the journey starting point and the destination. Taking into account the route parameters and the travel condition, a target speed of travel of the vehicle along the determined travel route is determined, wherein the travel route is divided into a plurality of segments and the division of the travel route into segments takes place based on the route parameters and/or the travel condition.
A method and a device for determining the driving strategy of a motor vehicle is known from DE 10 2007 036 794, wherein for a specified travel route a corridor for a possible target speed of travel with an upper and a lower speed limit is defined over the travel route.
And a method for obtaining a data record is proposed in the unpublished DE 10 2010 047 080.5, in which the method reproduces the predicted speed of a vehicle over a plurality of points of a route or alternatively associates the speed with points in time that are defined in relation to travel on the route. The data record results in total in a speed profile for both alternatives.
The method for obtaining a data record according to DE 10 2010 047 080.5, which reproduces the predicted speed of a vehicle over a plurality of points of a route or of points in time when travelling the route as a speed profile, contains:                a) Providing a first data record, with which a plurality of routes are associated with route points,        b) Providing a second data record, with which a plurality of processes are defined, with which at least one input speed and one output speed are associated as defining variables,        c) Selecting a predetermined route using the first data record,        d) Determining a provisional speed profile for a journey of a vehicle over the predetermined route,        e) Dividing the route into route segments, each with an associated process from the processes defined in the second data record, using the provisional speed profile, and        f) Determining a speed profile for each associated process in e), wherein the determination takes place for individual processes or for groups of processes having successive processes, and for at least one of the individual processes or groups of processes it is hereby taken into account which process or which group of processes takes place before or afterwards.        
According to DE 10 201 0 047 080.5, initially a first data record is provided that associates route points with a plurality of routes or (partial) routes (possibly on a complete road network). Further, a second data record is provided, with which a plurality of processes is defined, wherein at least one input speed and one output speed are provided as defining variables. Within the context of providing the second data record, preferably only such processes are defined that each actually occur in accordance with its definition or at least in a similar form. For example, a process in which a vehicle accelerates from 0 km/h to 53 km/h, such as is characteristic of the acceleration at a traffic light in town after switching to “Green”. Or a process of the acceleration from 53 km/h to 85 km/h if the driver of the vehicle is leaving the city and there is a speed restriction of 80 km/h. Or an acceleration from 85 km/h to 130 km/h on the on ramp of a highway. The actual process of acceleration from 0 km/h to 130 km/h can thus comprise a plurality of partial processes.
According to DE 10 201 0 047 080.5, a selection of a predetermined route takes place and a provisional speed profile is determined for the route for the journey of a certain vehicle over the predetermined route. The division of the route, especially the complete division of the route, into route segments takes place, and indeed such that a process from the processes defined in the second data record is associated with each route segment. The division of the route takes place using the provisional speed profile. This enables a definitive speed profile to be obtained. With the method according to DE 10 2010 047 080.5, a speed profile is determined for each process for this purpose. That which takes place outside of a process is especially at least partly taken into account here. Thus for one thing a plurality of processes can be combined to form a group of processes, so to speak a new process, and a speed profile is associated with the entire group of processes.
According to DE 10 201 0 047 080.5, in at least one case the determined speed profile has the appearance that significantly depends on the adjacent process (or the adjacent group of processes). For example, the same constant speed from the provisional speed profile can be assigned differently depending on how the journey proceeds. When travelling at 40 km/h in town one regularly stops at traffic lights, i.e. brakes completely to 0 km/h. When travelling at 40 km/h out of town, a subsequent acceleration can take place such that the driver always accelerates a little in advance and then decelerates lightly again.
DE 10 2010 047 080.5 makes use of the concept of a “process”, with which an input speed and an output speed are associated; the concept is introduced of defining situational contexts. The use of the concept of a “process” also goes beyond associating an average time to simple determined routes and associating the same to a determined branch in a graphical tree that symbolically reproduces the road network. The totality of the processes can and should especially have the property that travelling along a route can actually be divided into a plurality of processes without undefined situations remaining.
The concept of the process can be reflected by the concept of simple acceleration over a defined route, possibly with a defined gradient, (or simple constant travel or a simple deceleration) and by more complex contexts. Thus defining the processes is preferably arranged so that a speed profile that comprises a non-linear segment is determined between the input speed and the output speed for at least some of the processes. To some extent, intermediate values for the speed are specified, and these do not simply originate from a linear relationship. For example, a process can be associated with a driving maneuver in which the driver of the vehicle is travelling round a turn: he initially brakes the vehicle slightly, but then accelerates again out of the turn to the next straight line travel. By the measure of providing intermediate values for the speed, especially even conditions outside the highway can come into consideration. Thus a process can also take into account a statistically fluctuating variable in some respects: the vehicles may have to come to a complete stop before a traffic light, but it can also be that the vehicle actually accelerates slightly in order to be able to drive across the traffic light. That which takes place on average can be represented by a defined process in which braking takes place e.g. to a speed of >0 km/h, wherein accelerating then takes place again.
Also in DE 10 2010 047 080.5 a new type of modeling of a typical journey is proposed, in which a constant speed is desired: In reality the actual speed fluctuates slightly about the desired speed; this can be represented in a model by an oscillatory change of the speed. Thus preferably in the nonlinear segment a linear profile of the speed is superimposed by an oscillatory profile of the speed. Equally, a speed profile can also be specified in which a segment with linearly varying speed is interrupted by a segment in which the speed is increased or reduced spontaneously, especially to the extent that is possible within the scope of vehicle control. Preferably, following the interruption the process returns to the interrupted linear profile, either at a speed value at which the interruption took place or at a speed that would have occurred by continuing the linear profile over time without the interruption.
The method according to DE 10 2010 047 080.5 preferably includes that a plurality of routes are travelled and measurement values for vehicle speed are obtained during this at defined points of a route. The experience indirectly reflected in the measurement values is then made visible in a direct manner by defining a number (but preferably a finite number) of processes with which an input speed and an output speed are associated, and indeed the definition takes place based on the measurement values obtained.
From DE 10 2010 047 080.5 the known measure for distinguishing between a plurality of driving styles can be used particularly effectively. A plurality of driving styles can be assigned in the second data record (if sufficient data material are available). Certain processes can then be defined that match a defined driving style. By the determination of the driving style (selecting or assigning) it is then clear how many processes are relevant. Only one process from the processes in the second data record defined for exactly this driving style is assigned to each route segment.
Preferably, according to DE 10 2010 047 080.5, in addition the selected or assigned driving style is also already taken into account when determining the provisional speed profile. (For example, it can be assumed that with a certain driving style the maximum permitted speed will be exceeded by a defined amount etc., whereas with a different driving style it is assumed that an effort is made to exactly maintain the maximum permitted speed.)
With a preferred aspect according to DE 10 2010 047 080.5, information about the type of roads is also included in the data record provided in a) in a known manner, and said information is preferably also taken into account in f). The same applies to taking into account an input altitude and an output altitude, possibly also a gradient.
For later determination of the energy consumption when travelling the predetermined route, according to DE 10 2010 047 080.5 it can be helpful to determine the power to be applied to the wheels of the motor vehicle travelling the route using the final speed profile, and indeed in association with the points of a route or points in time at which the data of the data record are specified for the speed profile.
Using the final speed profile, in addition a number for specifying the quality of the prediction can be determined.
The method according to DE 10 2010 047 080.5 is preferably carried out within the context of operating a navigation device in a motor vehicle, but the use of alternative data processing devices is conceivable. In principle it is true that the first and second data records are stored in a memory of a motor vehicle, that c) is carried out using a control device in the motor vehicle and d) to f) are performed by a data processing of the motor vehicle.
As can be seen from the above representation, a forecast of a driving profile has always been based on data from a database and thus always comprises deviations from the real driving profile. A forecast can, however, only be optimally used if its quality is also known. Such a quality criterion did not previously exist.